Our proposal on the enzymic pathways responsible for the biosynthesis of alkyl and alk-1-enyl (plasmalogen) ether bonds in glycerolipids in cancer cells is a continuing project. Previous results from this project have shown that two principle mechanisms operate in the formation of these ether bonds: (1) A displacement reaction for the biosynthesis of alkyl glycerolipids that substitutes a long-chain fatty alcohol for the acyl moiety of acyldihydroxyacetone phosphate, and (2) The conversion of an alkyl group to an alk-1-enyl group for the biosynthesis of plasmalogens that requires an enzyme system possessing the properties of a mixed-function oxidase. Understanding the detailed chemical mechanisms underlying these reactions is expected to answer questions on why the ether lipids are associated with malignancy and to elucidate the biochemical nature of fundamental reactions that form complex glycerolipids which are essential components of biomembranes. Specific goals for the current proposal include: (1) Determining the sequence of phosphorylation in the alternate pathway that we recently discovered for the biosynthesis of the alkyl analog of phosphatidic acid, (2) Investigating the mechanism responsible for the substitution of an alcohol group for the acyl moiety of acyldihydroxyacetone-P, and (3) Solublizing the microsomal desaturase that forms ethanolamine plasmalogens so that physical and chemical properties of the components can be compared with those of fatty acid desaturases.